Iowa State NWRC study finds flaxseed lowers high cholesterol in men

03-17-10

Suzanne Hendrich, an ISU professor in food science and human
nutrition, led a study finding that men can experience some
cholesterol-lowering benefit from consuming flaxseed lignans.
Photo by Jaclyn Hansel, College of Human Sciences
(print
quality photo)

Iowa State NWRC study finds flaxseed lowers high cholesterol in men

AMES, Iowa -- A new study from Iowa State University's
Nutrition and Wellness Research Center (NWRC) may give men a
way to combat high cholesterol without drugs -- if they
don't mind sprinkling some flaxseed into their daily diet.

Suzanne Hendrich, an ISU professor in food science and human
nutrition, led a study that examined the effects of flaxseed
lignan in 90 people diagnosed with high cholesterol. The
results showed that consuming at least 150 milligrams of
flaxseed lignans per day (about three tablespoons) decreased
cholesterol in men, but not women, by just under 10 percent
over the three months that they were given the flaxseed.

While Hendrich admits that's considerably less than the
expected outcome from cholesterol-lowering drugs --
approximately 10 to20 percent for three months, depending on
the individual -- it's still enough to make flaxseed a more
natural option for some men.

"Because there are people who can't take something
like Lipitor, this could at least give you some of that
cholesterol-lowering benefit," Hendrich said. "The
other thing is, there are certainly some people who would
prefer to not use a drug, but rather use foods to try to
maintain their health. So this potentially would be something
to consider."

Americans suffer from high blood cholesterol

According to the Centers for Disease Control and Prevention,
about 17 percent of Americans suffer from high blood
cholesterol -- a fat-like substance found in the body that can
clog arteries and contribute to heart disease.

Hendrich developed the study with ISU master's student Kai
Ling Kong and doctoral graduates Zhong Ye, Xianai Wu, and
Sun-Ok Lee to determine whether the main lignan in flaxseed,
secoisolariciresinol diglucoside, could lower cholesterol.
They'll be presenting results of the research at the
American Society for Nutrition's annual meeting at
Experimental Biology 2010, April 24-28, in Anaheim, Calif.

The study's 90 subjects -- which included twice as many men
as women -- all had high cholesterol, but no other underlying
health conditions. The participants were divided into three
groups and were randomly assigned to daily consume tablets that
contained zero, 150, or 300 milligrams of flaxseed lignans for
12 weeks.

It's the flaxseed lignans -- a group of chemical compounds
found in plants that are known for their protective health
effects -- that may help lower cholesterol, according to
Hendrich. These compounds are converted to their bioactive
forms by gut microbes. Hendrich reports that they made a
healthy conversion in the subjects in this study, with no
adverse health consequences.

No cholesterol-lowering effect in women

While the study found that the flaxseed lignans lowered
cholesterol in men, it did not produce a significant change in
women.

"We're really puzzled about that because we were
looking at post menopausal women and these lignans are known as
plant estrogens, so they have a very weak but measurable
estrogen effect," Hendrich said. "So potentially,
they would have a mild effect for substituting some estrogens
in women. It's really hard to know why [there was no effect
in women] and whether these substances are counteracting,
possibly, some testosterone in men, which of course women
don't have. It's definitely something we'd like to
investigate further."

Hendrich reports the flaxseed lignan tablets used in this study
are not currently available in the U.S. to her knowledge. In
the absence of tablets, she says flaxseed can also be sprinkled
on cereal, or added in a muffin mix or bread, although whole
seeds are not very digestible. Ground flaxseed meal can also
provide the desired cholesterol-lowering lignans, according to
Hendrich, but it will oxidize over time and could potentially
affect the flavor of the foods that it's in. She points out
that the oxidation of the product also would diminish the
flaxseed's omega-3 fatty acids, which can prevent heart
attacks, so freshness is important in the product's impact.

The ISU researcher hopes to publish the study in a professional
journal. She also plans further investigation on whether
flaxseed can be taken in combination with other known
cholesterol-lowering substances, and whether it could prevent
high cholesterol in the first place.

The $190,000 research study was jointly funded by the Archer
Daniels Midland Company and Grow Iowa Values Fund.

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Quick look

A new study from Iowa State's Nutrition and Wellness
Research Center study found that men who consumed at least 150
milligrams of flaxseed lignans per day decreased cholesterol by
just under 10 percent over the three months that they were
given the flaxseed.

Quote

"Because there are people who can't take something
like Lipitor, this [flaxseed lignans] could at least give you
some of that cholesterol-lowering benefit. The other thing is,
there are certainly some people who would prefer to not use a
drug, but rather use foods to try to maintain their health. So
this potentially would be something to consider."